Reduction of line edge roughness with a conformal coating of a sealant

Abstract

A base-loaded polymer is applied to a semiconductor feature formed after exposing and developing a photoresist layer in order to reduce line edge roughness caused by a residual acid collecting on the edges of the feature during the post-exposure bake of the photoresist. Alternatively, a polymer is applied containing grains that are of suitable size for smoothing the line edge roughness.

1 . A method comprising;
 depositing a photoresist layer on a semiconductor wafer;   exposing and developing a portion of the photoresist layer to define a feature; and   applying a first substance to the semiconductor wafer to reduce line edge roughness of the feature.   
     
     
         2 . The method of  claim 1  wherein the first substance is a base. 
     
     
         3 . The method of  claim 2  further comprising a first baking of the photoresist layer to partially deprotect the photoresist. 
     
     
         4 . The method of  claim 3  further comprising a second baking of the feature. 
     
     
         5 . The method of  claim 4  wherein during the second baking, residual acid residing at an edge of the feature reacts with the base. 
     
     
         6 . The method of  claim 5  wherein the residual acid is neutralized by reacting with the base, resulting in a less line edge roughness in the feature than existed prior to the residual acid reacting with the base. 
     
     
         7 . The method of  claim 6  wherein the amount of base deposited is approximately less than or equal to the amount of residual acid. 
     
     
         8 . The method of  claim 7  wherein the first baking is shorter than the second bake. 
     
     
         9 . The method of  claim 1  wherein the first substance is a polymer having a grain size that is less than  5  nm. 
     
     
         10 . An apparatus comprising:
 means for depositing a photoresist layer on a semiconductor wafer;   means for exposing a portion of the photoresist layer to an incident radiation;   means for developing the portion to form a feature; and   means for applying a first substance to the semiconductor wafer to reduce line edge roughness of the feature.   
     
     
         11 . The apparatus of  claim 10  wherein the first substance is a base. 
     
     
         12 . The apparatus of  claim 11  further comprising a means for performing a
 post-exposure bake of the photoresist layer to partially deprotect the photoresist.   
     
     
         13 . The apparatus of  claim 12  further comprising a means for performing a final baking of the feature after the post-exposure bake. 
     
     
         14 . The apparatus of  claim 13  further comprising a means for introducing residual acid residing at an edge of the feature with the base. 
     
     
         15 . The apparatus of  claim 14  wherein the means for introducing is to facilitate residual acid being neutralized by the base. 
     
     
         16 . The apparatus of  claim 15  wherein the means for depositing the first substance is a thin coat process. 
     
     
         17 . The apparatus of  claim 16  wherein the means for introducing the residual acid with the base is a thin coat process. 
     
     
         18 . A process comprising:
 performing a post-exposure bake on a semiconductor wafer for a period of time and a temperature to partially deprotect a photoresist layer portion deposited on the semiconductor wafer;   developing the photoresist layer portion after performing the post-exposure bake;   applying a conformal coating of a sealant on the semiconductor wafer after developing the photoresist portion; and   performing a second bake on the semiconductor wafer after applying the conformal coating.   
     
     
         19 . The process of  claim 18  wherein, during the second bake, residual acid diffuses toward an edge of a feature formed the developing and reacts with a base within the base-loaded polymer. 
     
     
         20 . The process of  claim 19  wherein at least some of the residual acid is neutralized by the base. 
     
     
         21 . The process of  claim 20  wherein a line edge roughness of the feature is reduced by the residual acid reacting the base. 
     
     
         22 . The process of  claim 21  wherein a sensitivity of the photoresist layer portion is not substantially increased. 
     
     
         23 . The process of  claim 22  wherein the residual acid is of an approximately lesser or equal concentration than that of the base.